Conventionally, contact lenses are intended to allow lenses to be freed from a frame and to permit lenses to be applied directly to the eyeball with inferior sight so that the sight may be improved and it is desired, for example, that contact lenses do not injure the eyeball and do not give the eyeball a sense of incongruity. However, since contact lenses are transparent, thin, and small, it is often very difficult to seek the lens if it has dropped accidentally near one's feet, for example, when applying or removing it from the eyeball. Further, if one steps on the lens while looking for it, it will become unusable, so that it is demanded that a contact lens must be handled with utmost care. Further when one has lost the contact lens, the seeking will take much time naturally and if one has an urgent business, he must sometimes buy a new one again, so that it is required that the location of the lost contact lens can be easily confirmed.